This invention relates to a method for optically transmitting signals in measurement units, and a measurement system employing such optical transmission method.
It has hitherto been a normal method in the production process for television receivers or the like to inspect the assembling state using a plurality of measurement devices. For example, when inspecting the assembled state of television receivers by a plurality of measurement devices placed along a belt conveyor, it becomes necessary to transmit information signals between the measurement devices. For such case, it has been customary to perform signal transmission using communication systems such as RS232C or GPIB signal format.
However, such signal transmission makes use of electric cables, and insulation between the measurement devices cannot be achieved, so that there is a risk of circuit destruction due to the difference in the ground potential between the different measurement devices. Besides, connection by electric cables is not desirable because signal transmission by the cable is performed at a site where the noise is likely to be picked up, such as an assembly line.
In addition, it is difficult to raise the information transfer speed with the above enumerated communication systems, so that, if the number of measurement devices connected to the inspection system is increased, it becomes difficult to achieve smooth signal transmission.